Machine control



July 25, 1944. A. R. MccouRT 2,354,391

MACHINE CONTROL Filed July 3, 1942 4 Sheets-Sheet 1 Irzventar JrflurFM'Ja tor-Z July 25, 1944. A. R. MCCOURT MACHINE CONTROL Filed July 5,1942 4 Sheets-Sheet 2 Inventor J w w m m r 3E9: K849 O O E- Q .m

w f Lam mi d m 4 T W \N. m .w QM A July 25, 1944. A. R. McCOURT MACHINECONTROL Filed July 3, 1942 4 Sheets-Sheet 3 Lu N RN 1/ M g I m/entar Mgag/W zm July 1944. A. R. MccouR'r 2,354,391

MACHINE CONTROL Filed July 3, 1942 4 Sheets-Sheet 4 I\ Q t 2 b 5 Q l N TQ N w s: m m x U- k N s & TX w &

If 4H m a a q t b '1 Invenior fliiorn e ys Patented July 25, 1944 UNITEDSTATES PATENT OFFICE 2,354,391 MACHINE CONTROL Arthur R. McCourt, Butte,Mont. Application July 3, 1942, Serial No. 449,633

3 Claims. I (Cl. 172-239) The invention relates to improved means forcontrolling the operation of a machine by means of a conductive line orstrip on a prepared chart,

so as to make the machine substantially inde-- pendent of an attendantwhile in operation, and the prirrlary object of the invention is toprovide a simple, reliable, and relatively inexpensive arrangement ofthis character.

Other important objects and advantages of the invention will be apparentfrom a reading of the following description taken in connection with theappended drawings, wherein for purposes of illustration a preferredembodiment of the invention is shown.

In the drawings:

Figure 1 is a general top plan view of the device showing a preparedchart in position.

Figure 2 is a general vertical longitudinal sectional view taken throughFigure 1.

Figure 3 is a fragmentary transverse vertical sectional view takenthrough Figure 2 along the line 3-4 and looking toward the left in thedirection of the arrows.

Figure 4 is an enlarged fragmentary transverse vertical sectional viewtaken through Figure 3 along the line 4-4 and looking toward the rightin the direction of the arrows.

Figure 5 is a perspective view of one of the contact points.

Figure 6 is a fragmentary perspective view of the outer end of the leadscrew mechanism.

Figure '7 is a perspective view of the point carrier. I

Figure 8 is a schematic wiring diagram showing the electricalconnections involved in the device.

Figure 9 is a schematic view showing the conductive ink line moving in adirection at right angles to the lead screw.

Figure 10 is a schematic view similar to Figure 9 in which the ink linetakes an abrupt turn so that part of the line lies parallel with thelead SCI'CW.

Figure 11 is a similar view in which the ink line takes an abrupt turnin a direction parallel to the lead screw.

Figure 12 is a diagrammatic view of a servomotor forming a connectinglink between the electrical wire and the governor for the turbine.

Referring in detail to the drawings, the device may suitably comprise ahorizontal base 5 upon which normally rests a flat block 6 which ishinged on a transverse axis as indicated by the numeral 1 to the lefthand end of the base 5. A reversible electric motor 8 is mounted on theblock 6. The left hand end of the motor shaft is provided with a pinion9 which is adapted to be geared to the machine to be controlled. Thislink connection is indicated in Figure 12. The opposite end of the motorshaft is provided with a pinion III which is meshed with a gear I Iwhich is fixed on the lead screw 12 one smooth end portion of which ismounted in an L-shaped bracket 43 secured to the right hand portion ofthe top of the block 6, the outer and smooth end portion being journaledin a, bracket ll which is rigidly supported relative to the 'bracket [3.by means of fixed rods l5 and I6 which are anchored in the two blockson the upper and lower sides of the lead screw. The rods l5 and It alsofunction as slide guides which pass through the upper and lower smoothbores I1 and IS in the contact point carrier which is generallydesignated IS. The upper end portion of the carrier is provided with athreaded bore 20 located between the bores I1 and I8 in which the leadscrew I2 is threaded. The carrier I9 is preferably of dielectricmaterial or is suitably insulated and is equipped also with a footportion 2| which has longitudinally spaced binding post holes 22 and 23,respectively. Between the binding post holes are two laterallylongitudinally spaced pairs of contact point mounting holes. The contactpoints, of which there are two, are severally designated by the numerals26 and 21, although of similar construction and arrangement. Eachcontact point consists of an inverted U-shaped wire having alongitudinally inwardly deflected extension 28 on one leg thereof, thelower terminal of the extension being arranged to ride on the chart 29which is laid upon and fixedrelative to theturn table 30. wardly throughthe pairs of holes 24 and 25 so that the extensions 28 depend below thefoot portion 2| of the carrier to engage the chart, while the shorterleg remains above the level of the chart. Reclining J-shaped flatsprings 3| and 32 have their standard portions pressing downwardly onthe bight portions of the contact points as illustrated in Figure 4 ofthe drawings so as to urge the extensions 28 into engagement with thechart. The crook portions of the springs are anchored by the bindingpost screws 33 and 34 which are threaded in the binding post holes 22and 23 in the foot portion of the carrier.

The turn table 30 is a disk of suitable material to revolve evenly andpresent a level surface and includes a hub 35 from which depends areduced spindle 36 which is journaled in the base 5, the spindle havinga gear 31 on its lower end in mesh with the gear 38 of a suitablesynchronous driving mechanism, such as the clockworks 39 which drivesthe turn table 30 at a predetermined timed rate. The top of the turntable has a central hole 40 to receive the aligning lpin 4| on the lowerend of the bracket H of the lead screw mechanism, so that when the leadscrew mechanism is swung downwardly from an upwardly hinged position(not shown) to the operative p0- The arms of the contact point passdownsit-ion, the pin 4| is entered in the hole 40 to center and alignthe entire mechanism.

The chart 28 may be in the form of circular graph 42 divided intosegments by the radii 43 to designate time periods, and the top of thetime table is provided with a suitable mark 44 to enable lining up thechart-for starting and stopping positions in time. Drawn on the graph 42is the guide line 45 which may be in the form of a line drawn in Indiaor other electrically conductive ink, or in the form of a conductiveinlay or strip. The line 45 is wide enough so that both of the points 25and 21 can rest on the line together.

For operating the described mechanism for controlling a machine, thereversible motor 8 is connected as shown in Figure 8 to a manualreversing switch 46 which has the blade mountings 41 and 48 connectingto corresponding conductive armatures 49 and 50 which are operated by arelay magnet which is energized from the vacuum tube plate circuit cuton and off by the contact of the contact points with the line 45 on thechart. The armatures 49 and 50 severally disposed between armaturecontacts 52 and 53 and 54 and 55, respectively. The contacts 53 and 54are connected together and are connected by a wire 51 with one side ofthe 110 volt A. C. or D. C. line as indicated by the numeral 58, withthe field 55 of the reversible motor connected therein. The remainingside 60 of the power line is connected to the armature contact 52 and bymeans of the jumper 6| to the armature contact 55.

The chart 2! may be ordinary paper ruled in ink or printed. Only thecontrol line or curve 45 is drawn in conducting ink. It will be notedthat the contact points 25 and 21 can be moved to any place on the chartby operation of the turntable 30 by means of phonograph motor,clockworks, or similar operating mechanism, and/or by operation of theblock I 9 by means of the motor 8.

By way of illustrating employment of the device of the invention, let itbe supposed that it is desired to provide for varying current outputfrom an unattended and isolated hydroelectric station for a certainperiod of twenty-four hours, the chart 2! is divided into 24 equal partsrel resenting hours and to arrange that the turntable 30 turn at therate of one revolution in twenty-four hours. The pinion 9 on the shaftof motor 8 is connected to the control apparatus which is to be operatedover the twenty-four hour period, in accordance with the conductive lineor curve 45 on the chart, to produce the following variations in currentoutput:

Time

csocaccmw i The load curve is plotted on the chart in terms of kilowattsand hours and drawn with conductive ink.

It is to be noted that since the points 25 and 21 are mounted on blockl9 which is connected to the motor shaft through the lead-screw l2 andthe gears l0 and II, a certain definite number of revolutions of themotor 8 will be required to move the points a given distance along aradius of the chart. For example, supposing the motor shaft is in zeroposition when the points are at the zero reading of load on the chart,then it will require a given number of revolutions of the motor shaft tomove the points 25 and 21 to the load reading on the chart. Let thisnumber of revolutions be designated by the letter n.

The electric line follower does only one thing. It keeps the points onthe edge of the line or curve 45 as the curve moves under them. This isdone by the circuit which controls the direction of rotation of themotor 0.

Assuming that it is midnight and the device has been placed in operationand the chart is rotating, so that the line 45 is sliding under thepoints 26 and 21, the motor shaft is rocking a part of a revolution ineach direction, pushing both of the points onto the line 45 and thenreversing until one point comes off the line. The angular position ofthe motor shaft is at 0.3 n revolution above zero, since zerorevolutions is assumed to be the value when the points are at zero loadon the chart and n revolutions is the value when the points are at 1000kw. on the chart. The line now is at 300 kw., hence the 0.3 nrevolution. Nothing new happens until 1 oclock in the morning when thecurve shows that a drop from 300 kw. to 250 kw. is desired. Since themotor keeps the points on the curve, it must turn 0.05 n revolution topush them to the new position of the curve, making the motor stop whenthe 0.05 n revolution has been made, and start rocking as explainedabove. This condition remains until 2 oclock. The motor then makesanother 0.05 n. revolution in the same direction as at 1 oclock in orderto keep the points on the curve. No further revolutions of the motor aremade until 3 o'clock when the motor makes 0.01 n revolution to keep theoints on the line at kw., on the curve, or 0.190 n revolution abovezero. At 4 oclock the curve rises from 190 kw. to 420 kw., so that themotor shaft must make 0.230 n revolution in the opposite direction tokeep the points on the line.

It will be noticed that any load desired corresponds to a given numberof revolutions of the motor shai't from the zero position. This meansthat the motor shaft can be geared to the control apparatus of the powerplant with the following results:

Supposing that the plant ha a total capacity of 1000 kw., and with thegates wide open, it gencrates this amount. With the gates half open, itgenerates half load or 500 kw., and so on. By gearing the motor 8 to thegate controls through a suitable coupling, it can be arranged that at nrevolutions of the motor shaft the gates are wide open, at 0.5 nrevolution the gates are half open etc. This makes it possible tocontrol the future operation of the plant by means of a curve drawn onchart 29. The purpose of the pinion gear 9 on the motor shaft is,therefcre, to couple the controls of the machine to be operated to themotor of the electric line follower. This is, in effect, coupling thecontrols of the machine to the curve on the chart.

In operating the device, the prepared chart is placed on the turntable30 by grasping the support I4 and lifting. The entire lead-screw andmotor mechanism will pivot on hinge 1, so it will be out of the way,making it possible to place the chart on the turntable. The chart isthen turned the turntable 56 is then wound.

The points 26 and 21 on block l9 will be either inside the curve 45 oroutside of it when the lead-screw mechanism is lowered into place. Thdevice is then turned on" electrically, power being supplied to theelectric circuit.

Assuming that. after the chart has been placed on the turntable and thelead-screw mechanism has been lowered into place, the points come torest inside the curve, that is, at a point somewhere between the curveand the center the chart. When the power is turned on, the leadscrewdriven by motor 6 will either push the points toward the center of thechart or pull them out toward the curve, depending on the position ofthe switch 46, Figure 8.

It, at this time, the motor 6 pushes the points toward the center of thechart, it shows that switch 46 is in the position for making the pointsfollow the outside edge of the curve. By outside edge is meant theedgeof conductive ink lin 45 which is farthest from the center of the chart.

The operatormust now decide which edge of the linked curve or line hedesires the points to follow. If he wishes to hav them follow theoutside edge, he shuts off the power and turns gear Ill by hand untilthe points are between the curve and the edge of the chart. He thenturns on the power and the device is in operation.

Should the operator decide to have the points follow the inside edge ofthe line, and conditions are as described above (that on testapplication of power the Points are between the curve and the center ofthe chart and try to go toward the center), he simply throws the switch46 to its other position, turns on the power, and the device is inoperation, following the inside edge of the curve.

Supposing that in adjusting the device for operation the points havecome down at a point outside of the curve 45, that at a point betweenthe curve and the outer edge 01' the chart, on test application of powerthe points will either move toward the curve or away from it.

If the points move toward the curve (in this case toward the center ofthe chart), it means that switch 46 is set to make them follow theoutside edge of the conductive curve. If this is what the operatordesires, he leaves the power on. The device is operating as he wishes.

If the points move away from the curve (in this case, away from thecenter of the chart), it means that switch 46 is set to make them followthe inside edge of the line. If the operator wants them to follow theoutside edge, he simply throws the switch 46 toits other position. If hewants them to follow the inside edge of the curve, he leaves the switch46 as it is and moves the points by hand across the curve to some placebetween it and the center of the chart, and then turns on the power.

It is evident from the foregoing that the device will do one 0! twothings, depending on the position of the switch 46, namely:

(1) Follow the outside edge of the line 45, or

(2) Follow the inside edge of the line 45.

The operator, must arrange the switch 46 and manually move the points bymeans of the leadscrew so that they will move toward the curve when thepower is turned on. They will then automatically find the line andfollow it.

As explained before, there are no critical circult constants, thefollowing conditions being sufficient for the operating circuit shown inFigure 3 of the drawings: (1) The fC" voltage must be high enough toblock the vacuum tube 62, that is, cut oil the plate current when bothpoints 26 and 21 are on the ink line 45. (2) The vacuum tube 62 and the"B voltage must be chosen to fit the requirements of the relay 5|.

No heater connections have been shown for the vacuum tube 62, andbatteries are shown for simplicity in tracing the circuit and describingits operation. It will be understood that any of the usual methods ofenergizing the circuit such -as transformers and rectifier, may be used.l

Startingwith the manual reversing switch 46, X

in the motor armature circuit in the position shown in dotted lines,this connects point 41 to point 46 and point 46 to the other side of themotor armature, and assuming that at the instant of starting, bothpoints 26 and 21 are resting on the conductive line 45 as shown inFigure 8, it can be seen that the grid of the tube 62 is at a highnegative potential with respect to the cathode. This particular circuitconsists of the cathode of the tube 62, and the conductor 63 to point26, the I conductive line 45 from point 26 to point 21, the wire 64 tothe positive side of the 0" battery, the 0" battery, the wire 65 to thegrid of the tube. A negligible amount of current will also flow throughthe resistance 66 which is placed between the grid and cathode, but thisis immaterial at this time.

With the vacuum tube grid at a high negative potential as describedabove, no current can flow from the cathode to the plate. The tube isblocked." Under these conditions, no current is flowing in an part ofthe plate circuit which consists of the vacuum tube 62(cathode-toplate), the conductor 61 from the plate to relay coil 5|, therelay coil 5|, the conductor 66 from the coil to the positive side ofthe B battery, the- B battery, and the conductor 69 from the negativeside of the B battery back to the cathode of the vacuum tube.

With no current flowing in the plate circuit as described above, thereis no current flowing in the winding 5| of the relay, since it is a partof the circuit. There is no attraction oi the armatures 49 and 50, andthey remain in the position shown.

Under the above conditions, the current in the motor circuit takes thefollowing path: Power line to conductor 60 to conductor 6|, to relaycontact 55, to relay armature 50, through the conductor 10 between relayarmature 55 and point 41 on the manual reversing switch 46, to point 41on the manual reversing switch. With the switch 46 in the positionshown, current will flow from point 41 to point 46, then to the motorarmature 6, through it, back to the manual reversing switch to armature49 of the relay. Since the relay coil 5| is demagnetized, the relayarmature is in the position shown, so that the current will flow fromarmature 49 to contact 53 and conductor 51 to the motor field 59,through it and back to the power line conductor 56.

In this case at a given time, current is flowing upwardly through themotor field 59 and from left to right in motor armature 6. The directionof motor rotation will be such as to move the points 26 and 21 to eitherthe right or left. The direction of point motion is immaterial in thisdescription since it can be changed at will by means of the manualreversing switch which reverses the motor armature connections but doesnot aifect the field connections of the motor. Assuming that theoperator has decided to have the points 26 and 2! follow the right-handedge of the line 45, then the above conditions will cause the motor torotate in the direction which will pull the points 26 and 21 toward theright.

The motor will continue to run in this direction until it has pulledpoint 25 oil? of the line 45. It can be seen that point 25 will leavethe line 45 before point 21. In practice, the motor will reverse whennoint 25 leaves the line, but point 21 will still be on the line. Thereason for reversal of the motor, and the means whereby it is producedare set forth below.

Assuming that the motor has moved the points to the right until point 25is off the line 45, but point 21 is still on the line, the followingchanges taking place:

There is no longer a complete grid circuit because the point 26 is nolonger on the conducting line 45. battery is removed as far as use isconcerned because its circuit is open between point 25 and point 21. Thenegative cha ge which C battery had maintained on the {5541'} of thevacuum tube 52 now leaks off through the 10 megohm resistance 55,bringing the grid and cathode to approximately the same potential.

Removal of the negative charge on its grid allows the vacuum tube 62 toconduct current and the 3" battery circuit is now completed through thevacuum tube and current flows around the loop which also includes thewinding of the relay 5|. Current in the relay winding causes it toattract the armatures 49 and 50, pulling them away from contacts 53 and55 and engaging them instead with contacts 52 and 54, respectively.

The above relay operation reverses the motor since then current flowsfrom the power line down through conductor 50 as before, but can onlonger reach armature 50 through contact 55 because the armature hasbeen attracted to the relay magnet 5|, but instead, the current flows toarmature 49 through contact 52 which has been closed by the relay magnet5|. From armature 49. the current flows to point 45 on the manualreversing switch. The position of this switch not having been changed,the current flows through it to the right hand side of the motorarmature 5, through it and back to point 41 on the manual reversingswitch, through the switch to point 41 and then to armature 55, contact54, conductor 51, motor field 59, conductor 55 and back to the powerline. It will be noticed that the current flows upwardly through themotor field in both cases, and that when both of the points 25 and 21are on the conductive line 45 current flows from left to right in themotor armature, and that when point 26 is off the line 45, the currentfiows from right to left in the motor armature. As a result, the motorwill run in one direction when both points are on the line 45, and inthe opposite direction when one point comes off the line 45. Thedirection of rotation of the motor is continually changing since it mustbe running at all times. The direction of rotation at a given instant isdetermined by the position of the points 26 and 2! with respect to theline 45 at that instant.

Extreme conditions of operation The action of the device under the mostextreme conditions possible can be understood by reference to theenclosed Figures 9, and 11.

In Figure 9, the line 45, is moving at a right angle to the lead screwl2, so that the motion of the line 45 and point motion are at rightangles. The manual switch is set to make the points follow the loweredge of the line 45. Point 25 is off the line and point 21 is on theline. The motor pushes the points in the direction shown until bothpoints are on the line. This reverses the motor, so that it pulls thepoints until point 25 is oil again. The process is repeated continuouslyuntil the line 45 changes direction.

In Figure 10, the line 45 makes an abrupt turn, so part of it liesparallel to the lead screw I2. The points follow the line 45 as inFigure 9 until the corner is reached. At this time the line 45 moves outfrom under point 21. The motor pushes the points as shown. Point 25 goeson the line, but point 21 being still oil, the circuit is still open andthe motor continues pushing the points in the direction shown until theline changes direction. The line must sooner or later make a turn to theright, because no other kind of curve is encountered in practical work.

In Figure 11. the direction of the line 45 is abruptly changed to aposition parallel to the lead scre l2, but opposite from the Figure 10.

The points were following the lower edge as in Figure 9 until the cornerwas reached. At this juncture, the line reached a position where bothpoints rest on it. The circuit being thereby closed, the motor pulls thepoints downwardly until the line direction changes.

The connecting link mechanism between the electrical unit and thegovernor, shown in Figure 12, which controls the turbine gates, isthrough hydraulic servomotor unit while beginning with motor gear 5,motion is transmitted through gear train ll, 12 to rack on shaft 14through bearing support 15, and the motiion of link 16 will center aboutthe pivot at 55 transmitting such motion to piston rod 11, whichoperates as a control or relay valve in the cylinder.

The hydraulic unit will function as a controlling device. Oil from ahigh pressure pump. transmitted through pipe 15, will in a neutralposition be trapped and no motion occurring. Pipes l5 and 55 areconnected from extreme ends of control cylinder to oil pump reservoirexisting under no pressure. It is evident from the above, that the valvepiston and rod 11 will be free to move with very little resistance, andthe power supplied from gear 5 will be suillcient to move thislink-work. As piston with rod 11 moves in direction indicated by arrow Xof any slight amount, high pressure oil will now to chamber from pipe 15through oil pipe 52, transmitting pressure to large piston 55. Anyrequired force can be attained by relative diameter of pistons 55, and11. Motion of piston 55 will be transmitted to outer turbine gate ring55 through link 55 to fixed ring 51, positioning the gates to thepredetermined load requirement as plotted on the chart. The process ofobtaining equilibrium will be by link 15 pivoting about 75 in its newposition and gradually bringing piston and rod 11 to a neutral position,as in Figure 12, of no oil flow. Movement 01' rack and rod 14 in eitherdirection will cause change in gate position through the hydraulic unitand will become neutralized in this position.

Should the operator wish the points to follow the upper instead of thelower edge of the line Having described the invention, what is claimedas new is:

1. An electric line follower comprising a chart having a conductive lineformed thereon, means for supporting and moving the chart in apredetermined path and at a predetermined rate, a pair of spacedcontactors to ride upon the chart and make electrical contact with saidconductive line, electric motor means for moving said pair of contactorsrelative to the chart to follow along one edge of said conductive line,and coupling means on said electric motor means adapted to operatecontrol means to cause operation of a machine in accordance with thearrangement of the conductive line on the chart.

2. An electric line follower comprising a chart having a conductivelineformed thereon, means for supporting and moving the chart in apredetermined path and at a predetermined rate, a pair of spacedcontactors to ride upon the chart and make electrical contact with saidconductive line, electric motor means for moving said pair of contactorsrelative to the chart to follow along one edge of said conductive line,and coupling means on said electric motor means adapted to operatecontrol means to cause operation of a machine in accordance with thearrangement of the conductive line on the chart, a current source forenergizing said electric motor means, said motor means being reversible,a manual reversing switch in circuit between said source and set motormeans, said manual switch being arranged to be set to cause thecontactors to continuously follow along one edge or the other of saidconductor line.

3. A device of the character described comprising a base, a turntablemounted on the base. time controlled means for turning said turntable,an electric motor mounted on said base, said mOtOr having a shaft andcoupling means thereon for connection to drive control apparatus, anormally horizontal assembly hinged at one end P to said base and havingits free end portion overhanging the turntable when in horizontalposition, said assembly being adapted to be swung upwardly away fromsaid turntable, a chart on said turntable having a conductive line, saidchart being adapted to be placed and removed while said assembly is inan elevated position. a longitudinal feed screw on said assembly, anoperating connection between the shaft of the motor and said feed screw,a carrier slidably mounted on said assembly for movement along thecarrier and across the chart in either direction, said carrier beingthreaded on said screw, a pair of laterally spaced contactors dependingfrom said carrier for engagement with the chart and for electricalcontact with the conductive line thereon, and electrical means affectedby the contact of at least one of said contactors with an edge of saidconductive line on the chart whereby said motor means is automaticallyoperated in forward and reverse directions to maintain or return thecontactors into contact with said conductive line on the chart duringthe revolution of the turntable.

ARTHUR R. McCOURT.

